Electrical transformer or converter



(No Model.)

0. L. OOFPIN. ELECTRICAL TRANSFORMER OR CONVERTER.

No. 512,603. Patented Jan. 9, 1894.

WITNESSES INVENTM? g}; mMJw UNITED STATES PATENT OFFICE.

CHARLES L. COFFIN, OF DETROIT, MICHIGAN.

ELECTRICAL TRANSFORMER OR CONVERTER.

SPECIFICATION forming part of Letters Patent No. 512,603, dated January9, 1894.

Application filed December 11, 1891. Serial No. 414,715. (No model.)

T0 at whom it may concern.-

Be it known that 1, CHARLES L. ()oFFIN,ot Detroit, in the county oflVayne and State of Michigan, have invented a new and useful Improvementin Transformers or Converters, of which the following is aspecification.

My invention consists in an improvement in transformers or convertersfor electric currents,hereinafter fully described and claimed.

Figures 1 and 2 are side elevations of the secondary of a transformer.Fig. 3 is an elevation of the transformer showing the core and a portionof the primary. Fig. at is an elevation at right angles to Fig.

Electrical machines for the purpose of converting a current of highvoltage and low amperage into a current of low voltage and highamperage, or vice versa, are well known in the art, and are calledtransformers or converters. I therefore deem a detailed description ofthe construction and operation of such machines unnecessary, as theirgeneral construction and operation will be readily understood by anyelectrician from the name.

In all the figures, S represents the secondary coil of a transformer, ofwhich 0 is the core and P is the primary coil.

In using transformers to carry heavy currents, especially for electricwelding, great difficulty is experienced in the heating of the secondarycoil. I obviate this heating, and keep the secondary cool in use bymaking it perforated. As shown in Fig. 1, the secondary consists of ametal blank, preferably copper, perforated with holes. The secondary mayeither be a single large piece of metal, or may be made of a numberofpieces of thin perforated metal placed together as shown in Fig. 4.Instead of using perforated metal, the secondary may be made of a numberof blanks of woven metal cloth as indicated in Fig. 2. The core may beof any known construction, and only a portion of the primary coil isindicated in the drawings, as this'feature is well known. The effect ofthis ventilated secondary is not only to keep the secondary cool, but tokeep down the temperature throughout the whole transformer, but itnecessitates some increase in bulk in order to get the necessarycross-section in material.

What I claim as my invention, and desire to secure by Letters Patent, is

In a transformer or converter a secondary formed of perforated metal.

CHARLES L. COFFIN. iVitnesses: GERTRUDE H. ANDERSON, GEO. H. LOTHROP.

